1. Technical Field
The present invention relates to integrated circuits in general, and, in particular, to processing parameters within an integrated circuit. Still more particularly, the present invention relates to a method and apparatus for altering the electrical characteristics of circuits on a chip so that important circuit performance metrics are compensated for variations in processing parameters of devices within an integrated circuit.
2. Description of Related Art
Modern integrated circuit devices are typically mass-produced with a large number of critically-dimensioned features. In manufacturing, it is desirable to maintain the respective critical dimensions of each chip within a wafer constrained to certain respective values in order to ensure desired operating speeds and operational characteristics for the integrated circuits.
Each feature on each chip in a mass-produced wafer is the product of a succession of many process steps. Each process step is controlled by a combination of variable process parameters. Different combinations of variations in process parameter can occur on a random basis across the numerous process steps of a mass-production line on a chip-by-chip basis. Sometimes a specific combination of process parameters deviations is relatively innocuous but sometimes not, depending on which process parameters are deviated for a given chip and how their respective process steps interrelate to establish critical dimensions on that chip.
The present disclosure provides an improved method and apparatus for altering electrical characteristics of circuits so that they are independent of device parameter variations due to processing.